What internal structure is used in the TreeMap class to store elements?

In Java, the TreeMap class uses a data structure based on a red-black tree to store elements. This is a balanced binary search tree that provides ordered storage of keys and guarantees logarithmic time complexity for basic operations — insertion, deletion, and search.

A red-black tree maintains balance through coloring rules and rotations of nodes, which allows efficient operations even with a large volume of data.